Smith's five-yard touchdown catch late in the fourth quarter restored Calgary's lead en route to a 40-26 win over the B.C. Lions on Friday.
And with 130 yards in the game, Calgary's Jon Cornish broke his own single-season rushing record by a Canadian running back. The New Westminster, B.C., native extended his mark to 1,545 yards with three games remaining in the regular season.
Calgary moved six points clear of the Lions atop the CFL's West Division to 12-3. The Lions (9-6) lost their second in a row.
Smith signed as a free agent with Calgary last month and was activated from the practice roster this week.
The 28-year-old running back-return specialist from Fresno, Calif., played in the NFL's Pro Bowl in 2009 as a returner for the Tampa Bay Buccaneers. Smith last played in a football game a year ago in the United Football League.
"Every time I step on the field I feel like I'm capable of doing something big and my teammates blocked great for me and made my job easy," Smith said. "I've been preparing for this for a long time and I just cashed in on my opportunities."
The Edmonton Eskimos (3-11) host the Saskatchewan Roughriders (9-5) in another West Division game Saturday.
Calgary, B.C. and Saskatchewan have already secured playoff berths. The next three games will determine playoff matchups in the West.
The Stampeders are in Edmonton next Friday, host the Roughriders the following week and finish in Vancouver against the Lions on Nov. 1.
The Lions are at home for their final three games against Saskatchewan, Edmonton and Calgary respectively.
With Friday's victory, the Stampeders are the front-runners to host the division final and earn the semifinal bye.
"It does keep us in the driver's seat, so to speak," Calgary coach John Hufnagel said. "We have three tough ball games remaining and once it's all over, the dust settles and we find out where we stand."
An Edmonton upset of the Roughriders on Saturday would allow Calgary to clinch a home playoff berth.
Trailing until the fourth quarter, the Lions tied the game 26-26 at 6:47. But Stampeder defensive back Chris Randle sealed the win after Smith's touchdown with an interception and 65-yard runback to score at 13:53.
Smith was inserted into the lineup because non-import running back Matt Walter was out of the game with a concussion. Import Larry Taylor, the CFL's leader in total return yards, came out to make the import-non-import ratio work.
"Even though this was his first CFL game, with his experience that he brought from the other league, I was pretty sure the game wouldn't be too big for him," Hufnagel said of Smith. "He took advantage of an opportunity, made some big returns and did a tremendous job on the touchdown catch."
Cornish scored on a two-yard run and surpassed his previous rushing record of 1,457 yards in the opening quarter. He broke Norm Kwong's 56-year-old record in the final game of the regular season in 2012, so Cornish has time to make his numbers more gaudy.
Calgary quarterback Kevin Glenn threw touchdown passes to Marquay McDaniel and Smith.
Stampeders kicker Rene Paredes made four of his five field-goal attempts, including strikes from 43 and 45 yards in front of an announced 26,115 at McMahon Stadium.
Lions quarterback Thomas DeMarco, in his fourth start in the absence of the injured Travis Lulay, threw touchdown passes to Courtney Taylor and Nick Moore and scored on a one-yard plunge. DeMarco also threw a two-point convert to Taylor.
B.C.'s Paul McCallum was good on his one field-goal chance and contributed a punt single point.
"Certainly the guys fought back to tie the game," Lions head coach Mike Benevides said. "We didn't make enough plays. That’s a good football team over there and we couldn't get it done.
"Any time you play a game, all that matters is the result and winning the football game. We'll take a look at the tape and see what we can take out of it."
The Lions pulled even in the fourth quarter on DeMarco's six-yard touchdown pass to Moore and two-point convert throw to Taylor.
DeMarco, now 2-2 this season, completed 23 of 39 passing attempts for 301 yards and was intercepted twice.
Glenn was 22-for-37 in passing for 259 yards and picked off once. Glenn improved to 8-2 in his starts this season. Backup Drew Tate threw the ball once in the game and had three yards on two carries.
Calgary dominated time of possession in the first half with almost 21 minutes with the ball, but led just 19-11. B.C.'s ground game continued to struggle with just 56 rushing yards.
"You don't want to keep giving the ball to their team, especially at home," DeMarco said. "You want to make sure that you put everybody in a good situation and I wasn't able to do that today in the beginning.
"We've just got to come out and fix our mistakes. I'm sure we're going to watch film and see a lot of stuff that we could have done differently."